zend_interfaces.c

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/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) Zend Technologies Ltd. (http://www.zend.com)           |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: Marcus Boerger <helly@php.net>                              |
   +----------------------------------------------------------------------+
*/
 
#include "zend.h"
#include "zend_API.h"
#include "zend_interfaces.h"
#include "zend_exceptions.h"
#include "zend_interfaces_arginfo.h"
#include "zend_property_hooks.h"
 
ZEND_API zend_class_entry *zend_ce_traversable;
ZEND_API zend_class_entry *zend_ce_aggregate;
ZEND_API zend_class_entry *zend_ce_iterator;
ZEND_API zend_class_entry *zend_ce_arrayaccess;
ZEND_API zend_class_entry *zend_ce_serializable;
ZEND_API zend_class_entry *zend_ce_countable;
ZEND_API zend_class_entry *zend_ce_stringable;
ZEND_API zend_class_entry *zend_ce_internal_iterator;
 
static zend_object_handlers zend_internal_iterator_handlers;
 
/* {{{ zend_call_method
 Only returns the returned zval if retval_ptr != NULL */
ZEND_API zval* zend_call_method(zend_object *object, zend_class_entry *obj_ce, zend_function **fn_proxy, const char *function_name, size_t function_name_len, zval *retval_ptr, uint32_t param_count, zval* arg1, zval* arg2)
{
    zend_function *fn;
    zend_class_entry *called_scope;
    zval params[2];
 
    if (param_count > 0) {
        ZVAL_COPY_VALUE(&params[0], arg1);
    }
    if (param_count > 1) {
        ZVAL_COPY_VALUE(&params[1], arg2);
    }
 
    if (!obj_ce) {
        obj_ce = object ? object->ce : NULL;
    }
    if (!fn_proxy || !*fn_proxy) {
        if (EXPECTED(obj_ce)) {
            fn = zend_hash_str_find_ptr_lc(
                &obj_ce->function_table, function_name, function_name_len);
            if (UNEXPECTED(fn == NULL)) {
                /* error at c-level */
                zend_error_noreturn(E_CORE_ERROR, "Couldn't find implementation for method %s::%s", ZSTR_VAL(obj_ce->name), function_name);
            }
        } else {
            fn = zend_fetch_function_str(function_name, function_name_len);
            if (UNEXPECTED(fn == NULL)) {
                /* error at c-level */
                zend_error_noreturn(E_CORE_ERROR, "Couldn't find implementation for function %s", function_name);
            }
        }
        if (fn_proxy) {
            *fn_proxy = fn;
        }
    } else {
        fn = *fn_proxy;
    }
 
    if (object) {
        called_scope = object->ce;
    } else {
        called_scope = obj_ce;
    }
 
    zend_call_known_function(fn, object, called_scope, retval_ptr, param_count, params, NULL);
    return retval_ptr;
}
/* }}} */
 
/* iterator interface, c-level functions used by engine */
 
/* {{{ zend_user_it_new_iterator */
ZEND_API void zend_user_it_new_iterator(zend_class_entry *ce, zval *object, zval *retval)
{
    zend_call_known_instance_method_with_0_params(
        ce->iterator_funcs_ptr->zf_new_iterator, Z_OBJ_P(object), retval);
}
/* }}} */
 
/* {{{ zend_user_it_invalidate_current */
ZEND_API void zend_user_it_invalidate_current(zend_object_iterator *_iter)
{
    zend_user_iterator *iter = (zend_user_iterator*)_iter;
 
    if (!Z_ISUNDEF(iter->value)) {
        zval_ptr_dtor(&iter->value);
        ZVAL_UNDEF(&iter->value);
    }
}
/* }}} */
 
/* {{{ zend_user_it_dtor */
static void zend_user_it_dtor(zend_object_iterator *_iter)
{
    zend_user_iterator *iter = (zend_user_iterator*)_iter;
    zval *object = &iter->it.data;
 
    zend_user_it_invalidate_current(_iter);
    zval_ptr_dtor(object);
}
/* }}} */
 
/* {{{ zend_user_it_valid */
ZEND_API zend_result zend_user_it_valid(zend_object_iterator *_iter)
{
    if (_iter) {
        zend_user_iterator *iter = (zend_user_iterator*)_iter;
        zval *object = &iter->it.data;
        zval more;
 
        zend_call_known_instance_method_with_0_params(iter->ce->iterator_funcs_ptr->zf_valid, Z_OBJ_P(object), &more);
        bool result = i_zend_is_true(&more);
        zval_ptr_dtor(&more);
        return result ? SUCCESS : FAILURE;
    }
    return FAILURE;
}
/* }}} */
 
/* {{{ zend_user_it_get_current_data */
ZEND_API zval *zend_user_it_get_current_data(zend_object_iterator *_iter)
{
    zend_user_iterator *iter = (zend_user_iterator*)_iter;
    zval *object = &iter->it.data;
 
    if (Z_ISUNDEF(iter->value)) {
        zend_call_known_instance_method_with_0_params(iter->ce->iterator_funcs_ptr->zf_current, Z_OBJ_P(object), &iter->value);
    }
    return &iter->value;
}
/* }}} */
 
/* {{{ zend_user_it_get_current_key */
ZEND_API void zend_user_it_get_current_key(zend_object_iterator *_iter, zval *key)
{
    zend_user_iterator *iter = (zend_user_iterator*)_iter;
    zval *object = &iter->it.data;
    zend_call_known_instance_method_with_0_params(iter->ce->iterator_funcs_ptr->zf_key, Z_OBJ_P(object), key);
    if (UNEXPECTED(Z_ISREF_P(key))) {
        zend_unwrap_reference(key);
    }
}
/* }}} */
 
/* {{{ zend_user_it_move_forward */
ZEND_API void zend_user_it_move_forward(zend_object_iterator *_iter)
{
    zend_user_iterator *iter = (zend_user_iterator*)_iter;
    zval *object = &iter->it.data;
 
    zend_user_it_invalidate_current(_iter);
    zend_call_known_instance_method_with_0_params(iter->ce->iterator_funcs_ptr->zf_next, Z_OBJ_P(object), NULL);
}
/* }}} */
 
/* {{{ zend_user_it_rewind */
ZEND_API void zend_user_it_rewind(zend_object_iterator *_iter)
{
    zend_user_iterator *iter = (zend_user_iterator*)_iter;
    zval *object = &iter->it.data;
 
    zend_user_it_invalidate_current(_iter);
    zend_call_known_instance_method_with_0_params(iter->ce->iterator_funcs_ptr->zf_rewind, Z_OBJ_P(object), NULL);
}
/* }}} */
 
ZEND_API HashTable *zend_user_it_get_gc(zend_object_iterator *_iter, zval **table, int *n)
{
    zend_user_iterator *iter = (zend_user_iterator*)_iter;
    if (Z_ISUNDEF(iter->value)) {
        *table = &iter->it.data;
        *n = 1;
    } else {
        zend_get_gc_buffer *gc_buffer = zend_get_gc_buffer_create();
        zend_get_gc_buffer_add_zval(gc_buffer, &iter->it.data);
        zend_get_gc_buffer_add_zval(gc_buffer, &iter->value);
        zend_get_gc_buffer_use(gc_buffer, table, n);
    }
    return NULL;
}
 
static const zend_object_iterator_funcs zend_interface_iterator_funcs_iterator = {
    zend_user_it_dtor,
    zend_user_it_valid,
    zend_user_it_get_current_data,
    zend_user_it_get_current_key,
    zend_user_it_move_forward,
    zend_user_it_rewind,
    zend_user_it_invalidate_current,
    zend_user_it_get_gc,
};
 
/* {{{ zend_user_it_get_iterator */
/* by_ref is int due to Iterator API */
static zend_object_iterator *zend_user_it_get_iterator(zend_class_entry *ce, zval *object, int by_ref)
{
    zend_user_iterator *iterator;
 
    if (by_ref) {
        zend_throw_error(NULL, "An iterator cannot be used with foreach by reference");
        return NULL;
    }
 
    iterator = emalloc(sizeof(zend_user_iterator));
 
    zend_iterator_init((zend_object_iterator*)iterator);
 
    ZVAL_OBJ_COPY(&iterator->it.data, Z_OBJ_P(object));
    iterator->it.funcs = &zend_interface_iterator_funcs_iterator;
    iterator->ce = Z_OBJCE_P(object);
    ZVAL_UNDEF(&iterator->value);
    return (zend_object_iterator*)iterator;
}
/* }}} */
 
/* {{{ zend_user_it_get_new_iterator */
/* by_ref is int due to Iterator API */
ZEND_API zend_object_iterator *zend_user_it_get_new_iterator(zend_class_entry *ce, zval *object, int by_ref)
{
    zval iterator;
    zend_object_iterator *new_iterator;
    zend_class_entry *ce_it;
 
    zend_user_it_new_iterator(ce, object, &iterator);
    ce_it = (Z_TYPE(iterator) == IS_OBJECT) ? Z_OBJCE(iterator) : NULL;
 
    if (!ce_it || !ce_it->get_iterator || (ce_it->get_iterator == zend_user_it_get_new_iterator && Z_OBJ(iterator) == Z_OBJ_P(object))) {
        if (!EG(exception)) {
            zend_throw_exception_ex(NULL, 0, "Objects returned by %s::getIterator() must be traversable or implement interface Iterator", ce ? ZSTR_VAL(ce->name) : ZSTR_VAL(Z_OBJCE_P(object)->name));
        }
        zval_ptr_dtor(&iterator);
        return NULL;
    }
 
    new_iterator = ce_it->get_iterator(ce_it, &iterator, by_ref);
    zval_ptr_dtor(&iterator);
    return new_iterator;
}
/* }}} */
 
/* {{{ zend_implement_traversable */
static int zend_implement_traversable(zend_class_entry *interface, zend_class_entry *class_type)
{
    /* Abstract class can implement Traversable only, in which case the extending class must
     * implement Iterator or IteratorAggregate. */
    if (class_type->ce_flags & ZEND_ACC_EXPLICIT_ABSTRACT_CLASS) {
        return SUCCESS;
    }
 
    /* Check that class_type implements at least one of 'IteratorAggregate' or 'Iterator' */
    if (class_type->num_interfaces) {
        ZEND_ASSERT(class_type->ce_flags & ZEND_ACC_RESOLVED_INTERFACES);
        for (uint32_t i = 0; i < class_type->num_interfaces; i++) {
            if (class_type->interfaces[i] == zend_ce_aggregate || class_type->interfaces[i] == zend_ce_iterator) {
                return SUCCESS;
            }
        }
    }
    zend_error_noreturn(E_CORE_ERROR, "%s %s must implement interface %s as part of either %s or %s",
        zend_get_object_type_uc(class_type),
        ZSTR_VAL(class_type->name),
        ZSTR_VAL(zend_ce_traversable->name),
        ZSTR_VAL(zend_ce_iterator->name),
        ZSTR_VAL(zend_ce_aggregate->name));
    return FAILURE;
}
/* }}} */
 
/* {{{ zend_implement_aggregate */
static int zend_implement_aggregate(zend_class_entry *interface, zend_class_entry *class_type)
{
    if (zend_class_implements_interface(class_type, zend_ce_iterator)) {
        zend_error_noreturn(E_ERROR,
            "Class %s cannot implement both Iterator and IteratorAggregate at the same time",
            ZSTR_VAL(class_type->name));
    }
 
    /* Always initialize iterator_funcs_ptr. */
    ZEND_ASSERT(!class_type->iterator_funcs_ptr && "Iterator funcs already set?");
    zend_class_iterator_funcs *funcs_ptr = class_type->type == ZEND_INTERNAL_CLASS
        ? pemalloc(sizeof(zend_class_iterator_funcs), 1)
        : zend_arena_alloc(&CG(arena), sizeof(zend_class_iterator_funcs));
    class_type->iterator_funcs_ptr = funcs_ptr;
 
    memset(funcs_ptr, 0, sizeof(zend_class_iterator_funcs));
    funcs_ptr->zf_new_iterator = zend_hash_str_find_ptr(
        &class_type->function_table, "getiterator", sizeof("getiterator") - 1);
 
    if (class_type->get_iterator
     && class_type->get_iterator != zend_user_it_get_new_iterator
     && class_type->get_iterator != zend_hooked_object_get_iterator) {
        /* get_iterator was explicitly assigned for an internal class. */
        if (!class_type->parent || class_type->parent->get_iterator != class_type->get_iterator) {
            ZEND_ASSERT(class_type->type == ZEND_INTERNAL_CLASS);
            return SUCCESS;
        }
 
        /* The getIterator() method has not been overwritten, use inherited get_iterator(). */
        if (funcs_ptr->zf_new_iterator->common.scope != class_type) {
            return SUCCESS;
        }
 
        /* getIterator() has been overwritten, switch to zend_user_it_get_new_iterator. */
    }
 
    class_type->get_iterator = zend_user_it_get_new_iterator;
    return SUCCESS;
}
/* }}} */
 
/* {{{ zend_implement_iterator */
static int zend_implement_iterator(zend_class_entry *interface, zend_class_entry *class_type)
{
    if (zend_class_implements_interface(class_type, zend_ce_aggregate)) {
        zend_error_noreturn(E_ERROR,
            "Class %s cannot implement both Iterator and IteratorAggregate at the same time",
            ZSTR_VAL(class_type->name));
    }
 
    ZEND_ASSERT(!class_type->iterator_funcs_ptr && "Iterator funcs already set?");
    zend_class_iterator_funcs *funcs_ptr = class_type->type == ZEND_INTERNAL_CLASS
        ? pemalloc(sizeof(zend_class_iterator_funcs), 1)
        : zend_arena_alloc(&CG(arena), sizeof(zend_class_iterator_funcs));
    class_type->iterator_funcs_ptr = funcs_ptr;
 
    memset(funcs_ptr, 0, sizeof(zend_class_iterator_funcs));
    funcs_ptr->zf_rewind = zend_hash_str_find_ptr(
        &class_type->function_table, "rewind", sizeof("rewind") - 1);
    funcs_ptr->zf_valid = zend_hash_str_find_ptr(
        &class_type->function_table, "valid", sizeof("valid") - 1);
    funcs_ptr->zf_key = zend_hash_find_ptr(
        &class_type->function_table, ZSTR_KNOWN(ZEND_STR_KEY));
    funcs_ptr->zf_current = zend_hash_str_find_ptr(
        &class_type->function_table, "current", sizeof("current") - 1);
    funcs_ptr->zf_next = zend_hash_str_find_ptr(
        &class_type->function_table, "next", sizeof("next") - 1);
 
    if (class_type->get_iterator
     && class_type->get_iterator != zend_user_it_get_iterator
     && class_type->get_iterator != zend_hooked_object_get_iterator) {
        if (!class_type->parent || class_type->parent->get_iterator != class_type->get_iterator) {
            /* get_iterator was explicitly assigned for an internal class. */
            ZEND_ASSERT(class_type->type == ZEND_INTERNAL_CLASS);
            return SUCCESS;
        }
 
        /* None of the Iterator methods have been overwritten, use inherited get_iterator(). */
        if (funcs_ptr->zf_rewind->common.scope != class_type &&
                funcs_ptr->zf_valid->common.scope != class_type &&
                funcs_ptr->zf_key->common.scope != class_type &&
                funcs_ptr->zf_current->common.scope != class_type &&
                funcs_ptr->zf_next->common.scope != class_type) {
            return SUCCESS;
        }
 
        /* One of the Iterator methods has been overwritten,
         * switch to zend_user_it_get_iterator. */
    }
 
    class_type->get_iterator = zend_user_it_get_iterator;
    return SUCCESS;
}
/* }}} */
 
/* {{{ zend_implement_arrayaccess */
static int zend_implement_arrayaccess(zend_class_entry *interface, zend_class_entry *class_type)
{
    ZEND_ASSERT(!class_type->arrayaccess_funcs_ptr && "ArrayAccess funcs already set?");
    zend_class_arrayaccess_funcs *funcs_ptr = class_type->type == ZEND_INTERNAL_CLASS
        ? pemalloc(sizeof(zend_class_arrayaccess_funcs), 1)
        : zend_arena_alloc(&CG(arena), sizeof(zend_class_arrayaccess_funcs));
    class_type->arrayaccess_funcs_ptr = funcs_ptr;
 
    funcs_ptr->zf_offsetget = zend_hash_str_find_ptr(
        &class_type->function_table, "offsetget", sizeof("offsetget") - 1);
    funcs_ptr->zf_offsetexists = zend_hash_str_find_ptr(
        &class_type->function_table, "offsetexists", sizeof("offsetexists") - 1);
    funcs_ptr->zf_offsetset = zend_hash_str_find_ptr(
        &class_type->function_table, "offsetset", sizeof("offsetset") - 1);
    funcs_ptr->zf_offsetunset = zend_hash_str_find_ptr(
        &class_type->function_table, "offsetunset", sizeof("offsetunset") - 1);
 
    return SUCCESS;
}
/* }}} */
 
/* {{{ zend_user_serialize */
ZEND_API int zend_user_serialize(zval *object, unsigned char **buffer, size_t *buf_len, zend_serialize_data *data)
{
    zend_class_entry * ce = Z_OBJCE_P(object);
    zval retval;
    zend_result result;
 
    zend_call_method_with_0_params(
        Z_OBJ_P(object), Z_OBJCE_P(object), NULL, "serialize", &retval);
 
    if (Z_TYPE(retval) == IS_UNDEF || EG(exception)) {
        result = FAILURE;
    } else {
        switch(Z_TYPE(retval)) {
        case IS_NULL:
            /* we could also make this '*buf_len = 0' but this allows to skip variables */
            zval_ptr_dtor(&retval);
            return FAILURE;
        case IS_STRING:
            *buffer = (unsigned char*)estrndup(Z_STRVAL(retval), Z_STRLEN(retval));
            *buf_len = Z_STRLEN(retval);
            result = SUCCESS;
            break;
        default: /* failure */
            result = FAILURE;
            break;
        }
        zval_ptr_dtor(&retval);
    }
 
    if (result == FAILURE && !EG(exception)) {
        zend_throw_exception_ex(NULL, 0, "%s::serialize() must return a string or NULL", ZSTR_VAL(ce->name));
    }
    return result;
}
/* }}} */
 
/* {{{ zend_user_unserialize */
ZEND_API int zend_user_unserialize(zval *object, zend_class_entry *ce, const unsigned char *buf, size_t buf_len, zend_unserialize_data *data)
{
    zval zdata;
 
    if (UNEXPECTED(object_init_ex(object, ce) != SUCCESS)) {
        return FAILURE;
    }
 
    ZVAL_STRINGL(&zdata, (char*)buf, buf_len);
    zend_call_method_with_1_params(
        Z_OBJ_P(object), Z_OBJCE_P(object), NULL, "unserialize", NULL, &zdata);
    zval_ptr_dtor(&zdata);
 
    if (EG(exception)) {
        return FAILURE;
    } else {
        return SUCCESS;
    }
}
/* }}} */
 
/* {{{ zend_implement_serializable */
static int zend_implement_serializable(zend_class_entry *interface, zend_class_entry *class_type)
{
    if (class_type->parent
        && (class_type->parent->serialize || class_type->parent->unserialize)
        && !zend_class_implements_interface(class_type->parent, zend_ce_serializable)) {
        return FAILURE;
    }
    if (!class_type->serialize) {
        class_type->serialize = zend_user_serialize;
    }
    if (!class_type->unserialize) {
        class_type->unserialize = zend_user_unserialize;
    }
    if (!(class_type->ce_flags & ZEND_ACC_EXPLICIT_ABSTRACT_CLASS)
            && (!class_type->__serialize || !class_type->__unserialize)) {
        zend_error(E_DEPRECATED, "%s implements the Serializable interface, which is deprecated. Implement __serialize() and __unserialize() instead (or in addition, if support for old PHP versions is necessary)", ZSTR_VAL(class_type->name));
        if (EG(exception)) {
            zend_exception_uncaught_error(
                "During inheritance of %s, while implementing Serializable", ZSTR_VAL(class_type->name));
        }
    }
    return SUCCESS;
}
/* }}}*/
 
typedef struct {
    zend_object std;
    zend_object_iterator *iter;
    bool rewind_called;
} zend_internal_iterator;
 
static zend_object *zend_internal_iterator_create(zend_class_entry *ce) {
    zend_internal_iterator *intern = emalloc(sizeof(zend_internal_iterator));
    zend_object_std_init(&intern->std, ce);
    intern->iter = NULL;
    intern->rewind_called = 0;
    return &intern->std;
}
 
ZEND_API zend_result zend_create_internal_iterator_zval(zval *return_value, zval *obj) {
    zend_class_entry *scope = EG(current_execute_data)->func->common.scope;
    ZEND_ASSERT(scope->get_iterator != zend_user_it_get_new_iterator);
    zend_object_iterator *iter = scope->get_iterator(Z_OBJCE_P(obj), obj, /* by_ref */ 0);
    if (!iter) {
        return FAILURE;
    }
 
    zend_internal_iterator *intern =
        (zend_internal_iterator *) zend_internal_iterator_create(zend_ce_internal_iterator);
    intern->iter = iter;
    intern->iter->index = 0;
    ZVAL_OBJ(return_value, &intern->std);
    return SUCCESS;
}
 
static void zend_internal_iterator_free(zend_object *obj) {
    zend_internal_iterator *intern = (zend_internal_iterator *) obj;
    if (intern->iter) {
        zend_iterator_dtor(intern->iter);
    }
    zend_object_std_dtor(&intern->std);
}
 
static zend_internal_iterator *zend_internal_iterator_fetch(zval *This) {
    zend_internal_iterator *intern = (zend_internal_iterator *) Z_OBJ_P(This);
    if (!intern->iter) {
        zend_throw_error(NULL, "The InternalIterator object has not been properly initialized");
        return NULL;
    }
    return intern;
}
 
/* Many iterators will not behave correctly if rewind() is not called, make sure it happens. */
static zend_result zend_internal_iterator_ensure_rewound(zend_internal_iterator *intern) {
    if (!intern->rewind_called) {
        zend_object_iterator *iter = intern->iter;
        intern->rewind_called = 1;
        if (iter->funcs->rewind) {
            iter->funcs->rewind(iter);
            if (UNEXPECTED(EG(exception))) {
                return FAILURE;
            }
        }
    }
    return SUCCESS;
}
 
 
ZEND_METHOD(InternalIterator, __construct) {
    zend_throw_error(NULL, "Cannot manually construct InternalIterator");
}
 
ZEND_METHOD(InternalIterator, current) {
    ZEND_PARSE_PARAMETERS_NONE();
 
    zend_internal_iterator *intern = zend_internal_iterator_fetch(ZEND_THIS);
    if (!intern) {
        RETURN_THROWS();
    }
 
    if (zend_internal_iterator_ensure_rewound(intern) == FAILURE) {
        RETURN_THROWS();
    }
 
    zval *data = intern->iter->funcs->get_current_data(intern->iter);
    if (data) {
        RETURN_COPY_DEREF(data);
    }
}
 
ZEND_METHOD(InternalIterator, key) {
    ZEND_PARSE_PARAMETERS_NONE();
 
    zend_internal_iterator *intern = zend_internal_iterator_fetch(ZEND_THIS);
    if (!intern) {
        RETURN_THROWS();
    }
 
    if (zend_internal_iterator_ensure_rewound(intern) == FAILURE) {
        RETURN_THROWS();
    }
 
    if (intern->iter->funcs->get_current_key) {
        intern->iter->funcs->get_current_key(intern->iter, return_value);
    } else {
        RETURN_LONG(intern->iter->index);
    }
}
 
ZEND_METHOD(InternalIterator, next) {
    ZEND_PARSE_PARAMETERS_NONE();
 
    zend_internal_iterator *intern = zend_internal_iterator_fetch(ZEND_THIS);
    if (!intern) {
        RETURN_THROWS();
    }
 
    if (zend_internal_iterator_ensure_rewound(intern) == FAILURE) {
        RETURN_THROWS();
    }
 
    /* Advance index first to match foreach behavior. */
    intern->iter->index++;
    intern->iter->funcs->move_forward(intern->iter);
}
 
ZEND_METHOD(InternalIterator, valid) {
    ZEND_PARSE_PARAMETERS_NONE();
 
    zend_internal_iterator *intern = zend_internal_iterator_fetch(ZEND_THIS);
    if (!intern) {
        RETURN_THROWS();
    }
 
    if (zend_internal_iterator_ensure_rewound(intern) == FAILURE) {
        RETURN_THROWS();
    }
 
    RETURN_BOOL(intern->iter->funcs->valid(intern->iter) == SUCCESS);
}
 
ZEND_METHOD(InternalIterator, rewind) {
    ZEND_PARSE_PARAMETERS_NONE();
 
    zend_internal_iterator *intern = zend_internal_iterator_fetch(ZEND_THIS);
    if (!intern) {
        RETURN_THROWS();
    }
 
    intern->rewind_called = 1;
    if (!intern->iter->funcs->rewind) {
        /* Allow calling rewind() if no iteration has happened yet,
         * even if the iterator does not support rewinding. */
        if (intern->iter->index != 0) {
            zend_throw_error(NULL, "Iterator does not support rewinding");
            RETURN_THROWS();
        }
        intern->iter->index = 0;
        return;
    }
 
    intern->iter->funcs->rewind(intern->iter);
    intern->iter->index = 0;
}
 
/* {{{ zend_register_interfaces */
ZEND_API void zend_register_interfaces(void)
{
    zend_ce_traversable = register_class_Traversable();
    zend_ce_traversable->interface_gets_implemented = zend_implement_traversable;
 
    zend_ce_aggregate = register_class_IteratorAggregate(zend_ce_traversable);
    zend_ce_aggregate->interface_gets_implemented = zend_implement_aggregate;
 
    zend_ce_iterator = register_class_Iterator(zend_ce_traversable);
    zend_ce_iterator->interface_gets_implemented = zend_implement_iterator;
 
    zend_ce_serializable = register_class_Serializable();
    zend_ce_serializable->interface_gets_implemented = zend_implement_serializable;
 
    zend_ce_arrayaccess = register_class_ArrayAccess();
    zend_ce_arrayaccess->interface_gets_implemented = zend_implement_arrayaccess;
 
    zend_ce_countable = register_class_Countable();
 
    zend_ce_stringable = register_class_Stringable();
 
    zend_ce_internal_iterator = register_class_InternalIterator(zend_ce_iterator);
    zend_ce_internal_iterator->create_object = zend_internal_iterator_create;
    zend_ce_internal_iterator->default_object_handlers = &zend_internal_iterator_handlers;
 
    memcpy(&zend_internal_iterator_handlers, zend_get_std_object_handlers(),
        sizeof(zend_object_handlers));
    zend_internal_iterator_handlers.clone_obj = NULL;
    zend_internal_iterator_handlers.free_obj = zend_internal_iterator_free;
}
/* }}} */